A switched reluctance motor drive system has high fault-tolerance and reliability, and can continue its operation under certain fault conditions, owing to the mutual independence among the phases of the main circuit of the power converter and among the magnetic circuits of the phases of the motor. Therefore, the system can continue its operation and should not simply be deemed as system fault even when a constituting unit of the system fails, as long as the performance parameters of the system are still within a permissible range. Such outstanding fault tolerance performance introduces a new challenge in reliability study. For instance, suppose that the system can still operate after a unit of the system fails. What impacts on system operation will there be when a secondary fault occurs? How is an assessment of the system operation condition and reliability index performed after multiple levels of faults occur in the system? In the conventional modeling method based on a reliability block diagram, the system operation states are simplified into “normal state” and “failure state,” but a “fault operation state” is ignored. Therefore, that method cannot meet the requirements of reliability analysis of a switched reluctance motor drive system.